Insights into the landfill leachate properties and bacterial structure succession resulting from the colandfilling of municipal solid waste and incineration bottom ash

•The increased ratio of BA facilitates the leachate pH quickly entering neutral stage.•The increased ratio of BA promotes COD degradation and leachate humification process.•The more addition amount of BA, the more significant change in microbial community.•A high BA addition proportion has an inhibitory effect on the metabolism pathway.